Topobuf

Topobuf is a compact binary encoding for topographic data.

Topobuf provides lossless[^1] compression of TopoJSON data into protocol buffers. Advantages over using JSON-based formats alone:

• Very compact: typically makes TopoJSON 2-3 times smaller.
• Smaller even when comparing gzipped sizes: 20-30% for TopoJSON.
• Can store topology objects too large for JSON.stringify / JSON.parse
• Can accommodate any TopoJSON data, including extensions with arbitrary properties.

Sample compression sizes

| | normal | gzipped | |-----------------------|----------|---------| | pa-census-blocks.json | 280 MB | 44 MB | | pa-census-blocks.pbf | 114 MB | 35 MB | | us-zips.json | 15.02 MB | 3.19 MB | | us-zips.pbf | 4.85 MB | 2.72 MB | | idaho.json | 1.9 MB | 612 KB | | idaho.pbf | 567 KB | 479 KB |

Install

npm install topobuf

API

encode

var buffer = topobuf.encode(topojson, new Pbf());

Given a TopoJSON object and a Pbf object to write to, returns a Topobuf as a Buffer object in Node or UInt8Array object in browsers.

decode

var topojson = topobuf.decode(new Pbf(data));

Given a Pbf object with topobuf data, return a TopoJSON object.

See more

This library is based on geobuf by Mapbox, which provides similar functionality for GeoJSON

[^1]: When using quantized TopoJSON - nearly lossless otherwise